Slide rail is a mechanic device that is widely employed to carry an item, such as a drawer, a server or a UPS, to be slid relative to other structures. In the simplest way, the slide rail is composed of an inner rail and an outer rail, wherein the inner and outer rails are fixed onto two devices to be slid relative to each other, respectively. For example, the inner rail can be fixed on a UPS while the outer rail is fixed on a cabinet, and the inner rail is nested within the outer rail such that the UPS is mounted on the cabinet by means of the outer rail. In use, pushing a UPS will lead to the sliding of the inner rail fixed on the UPS relative to the outer rail under the guidance of the outer rail, thus causing the sliding of the UPS relative to the cabinet. Usually a UPS is pushed into or pulled from the cabinet.
Depending on specific applications, slide rail assembly can be improved in a more complicated way. For example, a slide rail assembly used for drawers which need to be pushed in and pulled out frequently may be provided with roller wheels, roller balls or even gear wheels between the inner rail and the outer rail to reduce the friction resistance between the inner and outer rails, so as to acquire a more smooth and stable operation. In addition, a damping may be provided between the inner and outer rails in order to prevent the damage to the slide rail assembly or other structures caused by an excessive applied force during operation. As to a slide rail assembly used for devices that need not to be operated frequently, such as a slide rail assembly used for installing a UPS on a cabinet, the smoothness of operation between the inner and outer rails is not so important in comparison to a slide rail assembly for drawers, and therefore no slide-aiding means is arranged between the inner and outer rails in normal cases. Moreover, for the purpose of improving the security of a slide rail assembly during use, a position limiting means or a positioning mechanism may be provided on the slide rail assembly.
Accordingly, the existing slide due to their simple structures could be neither satisfied for the requirements of smooth operation nor safety during use, or due to various additional mechanisms on the slide rail assembly for smooth and safe operation, leads to complex structures and high costs.